Vy. Levitsky et al., CORRELATION OF HIGH-TEMPERATURE STABILITY OF ALPHA-CHYMOTRYPSIN WITH SALTING-IN PROPERTIES OF SOLUTION, European journal of biochemistry, 219(1-2), 1994, pp. 231-236
A correlation between the stability of alpha-chymotrypsin against irre
versible thermal inactivation at high temperatures (long-term stabilit
y) and the coefficient of Setchenov equation as a measure of salting-i
n/out efficiency of solutes in the Hofmeister series has been found. A
n increase in the concentration of salting-in solutes (KSCN, urea, gua
nidinium chloride, formamide) leads to a many-fold decrease of the ina
ctivation rate of the enzyme. In contrast, addition of salting-out sol
utes has a small effect on the long-term stability of alpha-chymokypsi
n at high temperatures. The effects of solutes are additive with respe
ct to their salting-in/out capacities; the stabilizing action of the s
olutes is determined by the calculated Setchenov coefficient of soluti
on. The correlation is explained by a solute-driven shift of the confo
rmational equilibrium between the 'low-temperature' native and the 'hi
gh-temperature' denatured forms of the enzyme within the range of the
kinetic scheme put forward in the preceding paper in this journal: irr
eversible inactivation of the high-temperature form proceeds much more
slowly compared with the low-temperature form.